Moisture shield for spark plugs



Feb 24, 1948. l 5. G. BURRELL Er AL I 2,435,712

MOISTURE SHIELD FOR SPARK PLUGS Filed July is, 1946 4'/ JNVENToR.

G50/Q65 6. Q1/RMLL BY ARTHUQ l. HuLsH/zm AGI/vr Patented Feb. 24, 1948UNITED STATES PATENT GFFICE 2,436,112 MOISTURE SHIELD Fon SPARK PLUGSApplication July 13,' 1946, Serial No. 683,564

8 Claims. l

This invention relates to spark plugs and has particular relation tomeans for moisture proofing the electrical connection to such plugs.

It is the primary object of our invention to provide an improvedmoisture shield for use in conjunction with spark plugs and one which isadapted to protect the plug and its electrical connection from shortingout or becoming in-operative due to moisture conditions from causes suchas rain or condensation or the like.

Another primary object of our invention is the provision of a moistureshield which is adapted to be employed in conjunction with spark plugsof varying sizes and shapes.

A further object of our invention is the provision of a moisture shieldwhich is adapted to be employed in conjunction with spark plugs ofvarying sizes and shapes.

A further object of our invention is the provision of an extremelysimple moisture shield of this nature which may be manufactured at arelatively low cost and which may be quickly and easily installed.

It is a still further object of our invention to provide a moistureshield of this character having a resilient sealing member which is somounted as to eliminate the continual distortion and deformation towhich such devices of the prior art have been subjected.

It is another obiect of our invention to provide an improved sealbetween a moisture shield and the spark plug with which it is to beused.

Other and further features and objects of the invention will be moreapparent to those skilled in the art upon a consideration of theaccompanying drawings and following specication. wherein are disclosedexemplary embodiments of the invention, with the understanding, however,that such changes may be made therein as fall Within the scope of theappended claims, without departing from the spirit of the invention.

In the drawings:

Figure 1 is a view in elevation of a spark plug embodying a moistureshield constructed in accordance with a preferred embodiment of myinvention.

Figure 2 is an enlarged partial view of the same plug and moistureshield with the moisture shield shown in section to better illustratethe structure thereof.

Figure 3 is a view in section of a portion oi the moisture shield of thedevice shown in Figure 2, along with the preferred form of resilientsealing member.

Figure 4 is a view, partly in elevation and partly in section,illustrating the same moisture shield and sealing member when applied toa spark plug of a different shape. and

Figure 5 is a sectional view showing details of a modified form ofsealing member.

Referring now to these drawings, and in particular to Figures 1 to 3inclusive thereof; the spark plug which I have indicated generally at Ilincludes the hollow metal body I2 having the threaded portion I3 at itslower end, a porcelain insulator I4 extending upwardly through thecenter thereof, and a centrally disposed electrode I5 extending upwardlythrough the center of the porcelain insulator and terminating at the topthereof in the threaded terminal I6. The porcelain insulator illustratedin Figure 2 is one of the type having smoothly tapered side walls.

The moisture shield comprises in general a lower, flexible orrubber-like sealing member I1, a lower shield I8, disposed immediatelyabove the sealing member and secured in place by the pointed stylus I9which is threadedly received on the terminal I6. An upper shield 20 isadapted to support and provide a seal with the ignition cable 2|.

The lower sealing member I'I is preferably made of a rubber-likematerial such as Neoprene, which is also more or less heat and oilresistant. It may be made in the shape illustrated in Figure 3 with adownwardly cupped top wall 22 having straight side wall portions 23 atthe upper outer edge thereof, and an opening through the center as at 24for reception over the spark plug terminal I6. The annular-shaped,depending side walls 24 preferably converge inwardly at the bottom, andare also preferably of somewhat thinner section at the bottom, as shownAat 25.

The lower shield or body portion I8, preferably of molded plastic or thelike, is annular in shape with the bottom wall 26 thereof provided withan opening 21 for reception over the terminal I6 and also recessed as at28 to receive the upper wall 22 of the sealing member Il. The recess 28is preferably made with a substantially vertical slde wall portion 23A,and a downwardly and outwardly slanting face 29 as an aid in preventingthe entrance of any moisture. The annular upper portion 30 of the lowershield is threaded on its outside as at 3l to receive the internallythreaded upper shield 20. The well 32 within the upper portion of thelower shield provides for the reception of a washer 33 and the pointedstylus IS.

The stylus I9 is preferably turned from hexagonal stock so as to providea hexagonal base y as an aid in installing or assembling the device.

The upper shield 20, which may also be of molded plasticor the like, isgenerally conical in shape with an opening 35vthrough Vthe top thereoffor the reception of the ignition cable 2l. This opening 35is'preferably slightly tapered,

i and the stylus I 9' is of such length as to extend .out and expandlaterally to completely fill the recess 28 in the base of the lowershield I8. The annular, converging, sleeve-like side wall 24 ispreferably molded in such size as to engage the porcelain of arelatively small-size plug, and when the sealing member is installed onthe plug and caused to atten out by screwing the stylus i9 downwardly,the lower converging wa11s'24 tend to contract or converge even more andthus provide a tight seal against the porcelain of the plug.

It is now apparent that an electrical contact is established between theupper terminal IB of the spark plug and the centrally disposed conductorof the ignition cable 2l. A tightly sealed enclosure is provided toentirely enclose this electrical connection. No moisture may enter thisenclosure through either the opening 35 in the top shield, through thethreaded junction between the'upper and lower shields, through thesealed junction between the lower shield and the lower sealing member,or between the lower sealing member and the porcelain of the plug. Itwill be noted also that the sealing portion of the lower iiexiblesealing member serves only to provide a seal. It is not required tosupport the ignition cable or to stand any lateral strain and consequentdeformation due to the weight or to the frequent movement of theignition cable.

The same moisture shield structure and sealing member is illustrated inFigure 4 in conjunction with a spark plug having a porcelain insulatorof different shape, and illustrates the manner in which the lowersealing member I1 is adapted to closely engage and conform to thedifferent form of plug insulator 31.

'A modified form of lower sealing member and lower shield, asillustrated in Figure 5, is similar to the structure shown in Figure 3,except that the upper wall 38 of the lower sealing member 39 is notadapted to be expanded within the recessed bottom of the lower shield40. The lower shield 40 is recessed in such a. manner as to provide anarrow rim along its outer edge as at 4|, and the substantially straightor fiat top Wall 38 of the lower sealing member is caused to cupupwardly within the recess in the bottom of the lower shield wheninstalled over the terminal of the plug and substantially in the samemanner as in the device shown in Figure 2. A seal is thus providedbetween the lower sealing member 39 and the lower shield I0. The lowerconverging walls 42 of the lower sealing member are also urged inwardlyto closely engage the outer surface of the plug on which it isinstalled.

Although we have described specic embodiments of our invention, it isapparent that modifications thereof may be made by those skilled in theart. The lower sealing member may, for

example,` be made of somewhat differentshape than that shown ineither'Figure 3 or 5. The narrow ange 4I, providing the spacer betweenthe lower sealing member and the lower shield in Figure 5, may, ifdesired, be made integral with the sealing member rather than with thelower shield as shown. Such modifications may be made without departingfrom the spirit and scope of our invention as set forth in the appendedclaims.

What we claim is:

1. In a moisture shield for use with an ignition cable and a spark plughaving an insulator and a terminal at the top thereof; a lower sealingmember comprising an annular sleeve of rubberlike material, the diameterof the sleeve being reduced at the lower portion thereof for closelyengaging the insulator, the sleeve having a top Wall with an openingtherethrough for reception over the terminal of the plug, a lower shieldhaving the lower portion thereof recessed for the reception of the upperportion of the lower sealing member and having an opening therethroughfor reception over the terminal, a stylus threadedly engaged with theterminal and adapted to urge the lower sealing member into contact withthe lower shield and the insulator, the top wall of the lower sealingmember being curved so as to expand within the recess of the lowershield when secured by the stylus, and an upper shield threadedlyengaged with the lower shield and having an opening through the topthereof. the stylus adapted to expand and seal an ignition cabledisposed within the said opening.

2. In a moisture shield for use with a spark plug having van insulatorand a terminal at the top thereof; a shield having a recess in thebottom thereof and an opening through the center thereof for receptionover the terminal of the plug, a lower sealing member comprising anannular sleeve of rubber-like material, 'the diameter of the-lowerportion thereof being reduced to closely engage the insulator, the lowersealing member having a concave upper wall and an opening through thesaid wall for reception over the terminal, a stylus threadedly engagedon the terminal and adapted to expand and seal the lower sealing memberwithin the recess of the shield, and means providing an enclosure forthe stylus.

3. In a moisture shield for use with a spark plug having an insulatorand a terminal at the top thereof; a shield having a recess in thebottom thereof and an opening therethrough for reception over theterminal, an annular sleevelike sealing member having an -upper wallreceivable within the recess of the shield and having its lower portionconstricted to closely engage and provide a seal with the insulator, theupper wall of the sealing member having an opening therethrough forreception over the terminal and being generally cupped in shape, and astylus adapted to be threadedly engaged with the terminal above theshield and to force the shield downwardly, the cupped upper wall of thesealing member adapted, when forced downwardly, to flatten out and sealwithin the recess and to further constrict the lower, constrictedportion of the sealing member.

4. In a moisture shield for use with a spark plug having an upperterminal and an insulator; a lower shield recessed on the bottom thereofand having an opening through the top thereof adapted to be receivedover the terminal, the recess in the lower shield having a side wallextending generally vertical for at least a portion of its height, and asealing member of a rubber-like material disposed generally between thelower shield and the insulator, the sealing member having a top portionthereof adapted to be expanded within the recess of the shield so as toseal against the vertical Wall thereof, the sealing member having asleeve-like wall extending downwardly from the top portion thereof andinwardly to provide a seal with the insulator.

5. In a moisture shield for use with a spark plug having an insulator'and an upper terminal; a lower shield having an opening therethroughfor reception over the terminal, a flexible, rubberlike sealing memberhaving a cupped top portion disposed between the lower shield and theinsulator, the sealing member also having depending and inwardlyconverging, sleeve-like side wall portions, the lower edges thereofbeing adapted to be urged into a rm sealing contact with the insulatorby downward pressure of the lower shield upon the cupped sealing member,and a nut threadedly received on the terminal to force the lower shielddownwardly.

6. In a moisture shield for use with an ignition cable and a spark plughaving an insulator and a terminal at the top thereof; means providingAan electrical connection between the terminal and the cable, means,including a lower shield, providing a moisture-proof enclosure for thecable and terminal, and means providing a moisture-proof seal betweenthe lower shield and the insulator .comprising a exible rubber-likesealing member having a top wall with an opening therethrough adapted tobe received over the terminal and below the lower shield, asleeve-likewall depending from the top wall and converging inwardly, at the bottomthereof, toward the `insulator, spacingmeans disposed between the topwall of the sealing member, adjacent the edges thereon-and the lowershield, and a nut engaged on the terminal and adapted to draw the lowershield, the exible sealing means and the insulator together to form aseal therebetween.

'7. In a moisture shield for use with an ignition cable and a spark plughaving an insulator and a terminal at the top thereof; means providingan electrical connection between the terminal and the cable, meansincluding a lower body portion, providing a moisture-proof enclosure forthe terminal and the end of the cable, means providing a moisture-proofseal between the lower body portion and the insulator comprising aflexible, rubber-like sealing member having a top wall with an openingtherethrough adapted to be re- 5 ceived over the terminal and below thelower body portion, a sleeve-like wall depending from the top wall andadapted to contact the insulator to provide a seal therebetween, a nutengaged on the terminal and adapted to urge the lower l0 body portionand the sealing member toward the insulator, and spacing meansassociated with the lower body portion adapted to urge the outerportions and the sleeve-like wall of the sealing member downwardly andthe lower edge thereof inwardly toward the insulator.

8. In a moisture shield for use with an ignition cable and a spark plughaving an insulator and a terminal at the top thereof; means providingan electrical connection between the terminal and the cable, meansincluding a lower body portion, providing a moisture-proof enclosure forthe terminal, means providing a moisture proof seal between the lowerbody portion and the insulator comprising a flexible, rubber-likesealing member having 'a top wall with an opening therethrough adaptedto be received over the terminal and below the lower body portion, asleeve-like wall depending from the top wall and adapted to contact theinsulator to provide a seal therebetween, 3o and a nut 4engaged on theterminal above the lower body portion.

GEORGE G. BURRELL. ARTHUR L. HULSHIZER.

REFERENCES CITED The -followingreferences are of record in the le ofAthis patent:

7UNITED STATES PATENTS

